Experts Hunt For Clues To Mysterious Turtle Illness

January 26, 2001|By Stevenson Swanson, Tribune Staff Writer.

MARATHON, Fla. — When they are found alive, the 200-pound turtles are bobbing helplessly on the surface of the ocean. They are too weak to dive and escape their rescuers. They can barely move their flippers or flex their bony jaws.

They are the lucky ones. Since September, more than three times the usual number of dead loggerhead turtles have washed up on Florida beaches. Many are presumably the victims of a mysterious, paralyzing illness that is posing the newest threat to a 150 million-year-old species that already is in danger of extinction.

While many of the sick loggerheads are being cared for in this fishing and diving mecca in the middle of the Florida Keys, marine veterinary experts at the University of Florida in Gainesville are scrutinizing tissue samples, hoping to isolate the cause of the die-off. They have theories but no answers.

"It's a significant epidemic for two reasons," said Elliott Jacobson, a specialist in reptile infectious diseases at the university's veterinary college who is coordinating the scientific detective work. "One, it's never been seen before. Two, they're not recovering very well, even in the best of conditions for care. That makes one suspicious that large numbers are dying in the wild."

Because of the uncertainty involved in measuring turtle populations, let alone ailing or dead turtles that may never be found, the extent of the epidemic is difficult to estimate, Florida marine officials say.

Since the first sick loggerheads were picked up in September, 41 live turtles have been reported with the illness in a swath of Florida that stretches roughly from Ft. Myers on the gulf coast to Vero Beach on the Atlantic coast. Most were spotted in the waters around the Keys by recreational boaters and commercial fishermen, and many have since died.

In addition, 95 dead loggerheads were found on Florida beaches in the last three months of 2000, three times the normal number. Many were too decomposed to allow the cause of death to be determined, but such a large jump in the number of dead turtles leads officials to believe that the mysterious ailment was responsible for much of the increase.

"It's likely that we only see 10 percent of what's going on," said Allen Foley, a sea turtle specialist at the Florida Marine Research Institute in St. Petersburg. "I'm worried that there are a lot more dead and dying floating out there, because in the Keys there's more ocean than land. It would be easy for the carcasses to float out to the ocean and disappear."

Loggerheads, named for their massive, blunt heads, are one of several large sea turtles found in Florida waters, including green turtles, hawksbill turtles, Kemp's ridley turtles, and the largest of the group, leatherback turtles, a species that can grow to 8 feet long and weigh 2,000 pounds.

Sea turtle populations have suffered worldwide from a combination of man-made problems, including becoming entangled in fishing lines and traps, being run over by motorboats, becoming disoriented by lights as they try to find nesting sites at night, and losing thousands of eggs when beach vehicles and other equipment crush the nests that females dig on sandy beaches.

Loggerheads are classified as endangered worldwide, making it illegal to hunt or trade in them. Florida, with a nesting population of about 20,000 loggerheads, accounts for about one-third of the global total. Until the turtles started dying last fall, the state's loggerhead counts had mostly been steady or slightly increasing in recent years, although loggerhead numbers along the Atlantic coast from north Florida to Virginia continued to fall.

Many of the ailing turtles are being cared for in a makeshift intensive care unit set up at Marathon's unique Turtle Hospital, a private facility where sick or injured sea turtles are cared for and researchers from the University of Florida study turtle diseases.

The hospital's stainless steel examination tables and high-tech diagnostic equipment have been pushed aside to make way for nine bright blue and purple plastic swimming pools meant for toddlers. They now hold nine nearly motionless turtles.

In the eerily quiet rooms, the only sound from the normally energetic reptiles is an occasional long, gasping breath.

The pools have been emptied because, as hospital owner Richie Moretti explained, the turtles were too weak to lift their heads to breathe. The animals, whose barnacle-encrusted shells are about 4 feet long, rest on wooden planks to prevent the heavy shells from cutting off circulation to their rear flippers. Disposable pads under their tails and chins absorb urine and drool.

"We've never kept turtles out of the water like this," said Moretti, 57, a retired car dealer who pays for the hospital's operation with revenue from his adjacent motel. "This is a whole new thing."